Thank you all for the lovely advice!
Today I went out with all the halters and lead ropes, and they both ran right up to me??
I haltered the alpha, who is typically easier anyway, and held her by the lead rope. I grabbed a brush and gave her a light brushing, and the other came over and acted sort of jealous. So I slid a halter on her, and gave her a brushing, too! I kept it quick, was only out there for about 15 minutes alternating brushing between the 2. Then I pulled off both halters, fed a couple treats, and walked off. They followed me all the way to the gate, even though I was carrying all the jingling halters and ropes.
I'm really happy with how this is going - I was scared it was going to be another 2 hours in the pasture today!
I'm assuming I just keep going out there, alternating between brushing, catch and release, and actually working them? I seem to remember reading something like that, but can't find the article anywhere now!